The purpose of this grant is to study the effects of varying Ti02 surfaces on the adsorption of C3 from plasma, in reference to determining what properties of Ti02 layer are important to the biocompatibility of dental implants. Plasma enriched with 125I labeled C3 will be exposed to various Ti02 surfaces including; 1) anodic, 2) thermal, 3) electropolished, 4) machined, 5) anatase, 6) rutile. Hydroxyapatite will be used as a control surface. Exposure times include initially, 10, 100, 500, 1000 and 2000 seconds. Exposure solutions include 0.5, 1.0, 1.5, 2.0 and 100% plasma. C3 surface concentrations will be measured from cpm obtained via a gamma counter. The kinetics of C3 adsorption on Ti02 surfaces will be analyzed. Future work, not included in this grant proposal, includes extensive materials analysis of the surfaces and the creation of a mathematical model of protein adsorption as a function of both biological and materials variables.